1. Field of the Invention
This invention relates to apparatus for catching balls used in oil and gas wells, and more particularly, to a ball catcher adapted for use in a downhole drill pipe or tool string for catching and holding resilient wiper balls and providing an indication at the surface to determine the location of the balls.
2. Description of the Prior Art
It is well known in the art to use resilient balls, made of materials such as rubber, in well bores and downhole tool strings. Such balls are used to wipe the inner surface of the well bore or tool string as the ball moves downwardly and also to separate fluids. One typical application for these balls is in squeeze cementing jobs.
The balls are generally placed into the well at the surface using ball injector apparatus or released from a plug container. Some ball injector apparatus are disclosed in U.S. Pat. Nos. 2,961,045 to Stogner and 2,961,046 to Moeller et al., both assigned to the assignee of the present invention. Once the balls are released, it is desirable to catch or retrieve them so that they do not interfere with tool operations. One ball catcher used at the surface to catch resilient baffle balls and fracturing balls is disclosed in U.S. Pat. No. 4,420,040 to Arbasak et al., also assigned to the assignee of the present invention.
There is a need for a ball catcher used in a downhole drill pipe or tool string which can catch and hold resilient balls. There is also a need for a ball catcher which can provide an indication to a well operator that the ball has reached and entered the ball catcher, thereby providing the operator with information of the location of specific fluids in the tool string. The present invention meets this need by providing a ball catcher for use in a drill pipe or tool string and which gives surface pressure indications that the ball has reached the ball catcher and has entered it to be held therein for any number of balls to be caught in the operation.